The described invention relates in general to a cutting devices used in pencil sharpeners and the like, and more specifically to a dual fly-away cutter-carrier assembly for use in pencil sharpeners of various types. Certain aspects of this invention may be used with electric sharpeners that are consumer products or that are intended for commercial or industrial applications.
Commercially available electric pencil sharpeners may include cutter-carriers (i.e., the cutting assembly within the pencil sharpener that actually sharpens the pencil) having single helical cutters utilizing various “fly-away” cutter designs. In such products, the sharpened pencil point typically contacts a moveable plate at the end of a conical bore that is part of the cutter-carrier, thereby causing the cutter to be moved away from the pencil in a direction out of the conical bore, thereby greatly reducing or eliminating further sharpening of the pencil. Some of these products also include a mechanical linkage to the pencil-tip plate that extends outside the cutter carrier for the purpose of triggering an electrical switch to provide motor shut-off or a visible and/or potentially audible indication that the sharpening process is complete.
Other commercially available electric pencil sharpeners with electric stop or motor shut-off capabilities provide cutter-carriers having two separate cutters, but without the fly-away feature. Such sharpeners do, however, typically include the pencil-tip moveable plate and mechanical linkage thereto that extends outside the cutter carrier. These products do not rely on the removal of the helical cutters from the conical bore that is part of the cutter-carrier for indicating that sharpening is complete, but rather on motor shut-off or a visible and/or potentially audible indicator. In such products, one of the two helical cutters is typically foreshortened to provide adequate space within the cutter-carrier assembly for the pencil-tip plate. In this arrangement, the portion of the cutter that usually sharpens the harder and more abrasive core material of the pencil is removed, leaving, as in single-cutter designs, just one helical cutter that must absorb the primary wear associated with sharpening pencils or other items. Furthermore, when two cutter systems that include a mechanical-linkage feature are used to shut off the electric motor, because the cutters are fixed in relation to the conical cavity of the carrier, the cutting edges of the cutters are usually still engaged with the pencil casing and core when sharpening stops. This often results in undesirable resistance to removing the pencil from the sharpener. Accordingly, there is an ongoing need to for a dual cutter-carrier assembly that includes the fly-away feature, but that does not suffer from the inadequacies discussed above.